What makes a great Singer and what keeps his Vocal Longevity?

Careers are short lived these days — it did not use to be like that. Singers sang until the day they died. Their voices rang out way beyond today's “accepted” years without vocal problems that needed cortizone and surgeries, etc. Why? WHAT HAS CHANGED? Is it true that after age 50 there is no expectation of remaining “in voice”? Is it true that a 10-15 year career is all that can be expected of a voice? Is it true that after a 'certain age' the voice begins to lose height, depth, and begins to wobble, etc? Is it true that if you’re singing a specific "Fach" you cannot sing anything else or everything? These questions are asked of me always... Please join me for the answers and get blown away --- whatever you think --- this work will change your mind and your life and put you in touch with what is really possible!